RF, Micro- and Millimeterwave Capabilities

DA-Group designs and manufactures advanced spaceflight, RF, microwave and digital systems, subsystems and units. We also have a strong history of technology development, which is continued in LNA and MMIC development for space applications. DA-Group operates as a subcontractor to major satellite large scale integrators (LSI) and directly to the European Space Agency (ESA) and other international space organisations. Our design, procurement, manufacturing and test activities are performed to international quality standards, especially using those processes specified by ESA.

DA-Group has provided many significant systems for earth orbiting spacecraft and deep space probes. These are based upon RF and microwave units, with all necessary specialised DC supplies and computer control and monitoring equipment. RF equipments include Synthetic Aperture Radar (SAR), radar altimeters and high sensitivity radiometers. Systems have been provided with frequencies in the range 1.5 GHz to above 90 GHz. Technology developments have been demonstrated up to 300 GHz. We also have specialised knowledge in the design of active, in-flight calibration systems for radar and radiometers.

DA-Group provides full space quality, procurement and assembly, using basic components and pre-integrated units, procured and integrated to ECSS and ESCC procedures. All assembly is performed in a minimum class 100,000 cleanroom, with an integrate bonded store and all required test equipment. Many thermal and thermal vacuum chambers are available within the cleanroom, including a specialised vacuum system which can recreate space vacuum with temperatures down to 4K (-269 degree centigrade). EMC, vibration and mechanical shock testing is also available within house.

SPECIFIC DA-GROUP DEVELOPED UNITS

LNAs

High Power Amplifiers

Active Cold Loads for radiometer calibration

Synthetic Aperture Radar subsystems (SAR radar subsystems)

Projects

The MetOp-SG programme is being implemented in collaboration between EUMETSAT and ESA. DA-Group is developing 89 GHz radiometers, using highly sensitive LNA, previously developed by DA-Group over a ten-year programme, using MHEMT MMIC technology.

Sentinel-1 satellites

In 2016, DA-Group was awarded the repeat contract for the Sentinel-1 C and D satellites. Previously we have provided the following subsystems for Sentinel-1 A and B, which have been successfully operating since 2014 and earlier this year:

Transmit Gain Unit (TGU):This is a dual redundant, highly stable pulsed power amplifier used to provide the transmit signal power to feed the active transmit antenna array. It achieves exceptional stability, between pulses and within pulses, over the operating temperature range, using an FPGA bias control, monitoring semiconductor temperature and power levels.

RF Distribution Network (RFDN):This is implemented as divider (transmit) and combiner (receive) trees providing signal coupling between the radar electrincs and the antenna radiating elements. It comprises ~100 divoder/combiner units and almost 1,000 interconnection cables. A phase balance of less than 20 degrees, across the 140 radiating elements, was achieved using ultra-stable silicon-dioxide cables and a DA-Grouop developed system for measuring and selective matching of cables and units.

SES RF Harness: A further signal path extension of the RFDN, within the Radar Electronics system.

DA-Group performed the work as a subcontrator to Airbus Defence and Space UK, Airbus DS GmbH and OHB.

Leaf amplifier assemblies for TerraSAR-X and TanDEM-X

End customer EADS Astrium Germany and leaf amplifier assemblies also for PAZ EADS Casa, Spain. These are highly stable and accurate signal distribution units, used to divide transmit signals and combine receive signals in the SAR (Synthetic Aperture Radar) satellites. Satellites produce high resolution 3D images of the surface of the earth. The data is used to follow land usage and to predict and follow nature catastrophes.

Receiver for Planck

The Planck mission was launched to measure and map the Cosmic Microwave Background (CMB) radiation remnant from the “Big Bang” universe creation event. The mission enable the creation of CMB anisotropy maps which greatly advanced understanding of the mechanisms of early expansion.

DA-Group developed ultra-sensitive low noise amplifiers (LNA) which they then integrated in an array of 70 GHz radiometric receivers. To achieve the lowest noise levels, required to unmask the CMB signals, the receivers were cooled to 20 Kelvin. At this temperature, these were undoubtedly the most sensive receivers in the world, achieving an overall receiver noise tmperature 25K to 30K, over the frequency range from 63 GHz to 77 GHz.

SMOS, Calibration subsystems

The Soil Moisture and Ocean Salinity (SMOS) mission was launched to provide earth observations at L-band frequencies, using a sythetic aperture radiometer. This radiometer utilised many individual receivers extended in a three legged star configuration. Successful operation was fully dependant upon the highly accurate and instantaneous knowledge of relative receiver, gain and phase performances.

The DA-Group calibration system provided a continuous noise calibration signal to all receivers, allowing relative calibration. A second DA-Group system provided an absolute noise level for absolute calibration of the central three receivers. Both systems provided accurate calibration of the radiometer end data.

Radar altimeters for THE Huygens PROBE

Cassini/Huygens (NASA/ESA) mission to study the planet Saturn. After achieveing Saturn orbit, the probe Huygens was released and after a month cruise, entered the atmosphere of the moon Titan. During the aerobraking and parachute descent the probe made measurements of the atmosphere and surface. DA-Group provided two redundant radars, which gave altitude information for timing of landing and measurements. The return signal was also used to, generate an RF model the structure of the Titan surface.